This Program Project involves clinical neurology, genetic linkage analyses, and molecular genetic techniques and strategies to study neurogenetic disease. The program involves three cores and three projects. Project I involves the molecular studies of autosomal dominant spastic paraplegia (SPG). Project II proposes to define the complex underlying genetic etiology in autistic disorder. project III proposes to study autosomal dominant limb- girdle muscular dystrophy (LGMD). Core A is the Administrative Core and oversees the overall direction of the Neurogenetics Center as well as the financial aspects of the Center. Core B is the Mutation and Candidate Gene Resources Core and provides the technical resources an physical support for the project studies. Core C is the Family Ascertainment, Linkage Analysis and Informatics Core and provides family ascertainment, statistical analysis and databasing support for Projects I through III.